Apparatus for producing thin metal strip and method for producing thin metal strip using the same

ABSTRACT

A thin metal strip is produced by a single roll strip casting process, using a cooling roll, a tundish, and a molten metal remover. The cooling roll has an outer peripheral surface, on which it cools and solidifies molten metal while rotating. The tundish can accommodate the molten metal and supplies it onto the outer peripheral surface of the cooling roll. The molten metal remover is disposed downstream of the tundish in the rotating direction of the cooling roll with a gap A between the molten metal remover and an outer peripheral surface of the cooling roll, and removes a surface portion of the molten metal on the outer peripheral surface of the cooling roll to cut down the thickness of the molten metal to the width of the gap A.

TECHNICAL FIELD

The present invention relates to an apparatus for producing a thin metalstrip and a method for producing a thin metal strip using the apparatus.

BACKGROUND ART

It is known that rapid solidification process can provide metalmaterials with various properties. The rapid solidification processrefers to a process for solidifying molten metal at a certain coolingrate or higher. The rapid solidification process enables, for example,refining crystal structures of a metal material, homogenizing a solutedistribution, increasing a solid-solubility limit, producing amorphouslayers (amorphous), and producing thermodynamic non-equilibrium phases.Specifically, known methods for producing a cast piece by the rapidsolidification process include the strip casting process, the meltspinning process, the atomization process, the melt spinning process,and the like.

For example, International Application Publication No. WO2012/099056(Patent Literature 1) describes producing Si alloy by the atomizationprocess. For another example, Japanese Patent Application PublicationNo. 2013-161785 (Patent Literature 2) describes producing Si alloy bythe melt spinning process.

In the rapid solidification processes, the higher the cooling rate ofmolten metal is, the finer the resultant grains become. Among the rapidsolidification processes, one producing method with a particularly highcooling rate is, for example, the melt spinning process. The meltspinning process is a method in which molten metal is jetted and rapidlycooled on a roll rotating at high speed to produce a ribbon-shaped thinmetal strip in a flying manner. In the melt spinning process, a jet of asmall amount of molten metal is supplied onto the roll. Therefore, thecooling rate is high.

The melt spinning process enables the production of a thin metal stripincluding fine grains. However, in the melt spinning process, a smallamount of the molten metal is supplied onto the roll. Therefore, themelt spinning process has its limitation in production capability andhas a difficulty of producing a thin metal strip in volume.

Meanwhile, in the rapid solidification processes, a method capable ofproducing a thin metal strip in volume is, for example, a single rollstrip casting process. The single roll strip casting process is a methodfor producing a thin metal strip by continuously supplying molten metalonto a rotating roll to rapidly cool the molten metal. Methods forproducing a cast piece using the strip casting process are, for example,described in Japanese Patent Application Publication No. 2011-206835(Patent Literature 3) and Japanese Patent Application Publication No.2001-291514 (Patent Literature 4).

The producing apparatus described in Japanese Patent ApplicationPublication No. 2011-206835 (Patent Literature 3) is a producingapparatus for an aluminum clad plate. This producing apparatus includesa first roll with a cooling capability and a first pool for storingfirst molten alloy. The first pool is surrounded by a surface of thefirst roll, a first front plate, a rear member, and both-side members.The first front plate lies forward of the first roll in a rotationdirection. The rear member lies rearward of the first roll in therotation direction. The first front plate includes a front edge portionand is movably provided such that the distance between the front edgeportion and the surface of the first roll can vary. The first roll coolsthe first molten alloy in the first pool to form a first metallic layerin a semi-solidified state or a solidified state on the surface of thefirst roll and rotates with the first metallic layer. The first frontplate is urged so that the front edge portion of the first front platealways abuts against a semi-solidified surface of the first metalliclayer moving with the rotation of the first roll, at given force.

The producing method described in Japanese Patent ApplicationPublication No. 2001-291514 (Patent Literature 4) is a producing methodfor a negative electrode material for a non-aqueous electrolytesecondary battery. This producing method is characterized by melting analloy raw material having a composition selected such that a Si phaseand intermetallic compounds of Si and other metallic elements arecrystallized in solidification, and then solidifying the alloy rawmaterial using the strip casting process or the centrifugal castingprocess to form a columnar structure.

In the strip casting process, the amount of molten metal supplied onto aroll is large as compared with the melt spinning process. Therefore, thestrip casting process enables the production of a thin metal strip inlarge volume. However, in the strip casting process, the cooling rate ofthe molten metal is low as compared with the melt spinning process.Therefore, the strip casting process has a difficulty of refininggrains. For that reason, the strip casting process is requested toprovide more refined grains.

CITATION LIST Patent Literature

Patent Literature 1: International Application Publication No.WO2012/099056

Patent Literature 2: Japanese Patent Application Publication No.2013-161785 Patent Literature 3: Japanese Patent Application PublicationNo. 2011-206835 Patent Literature 4: Japanese Patent ApplicationPublication No. 2001-291514 SUMMARY OF INVENTION Technical Problem

The production methods disclosed in the Patent Literatures describedabove fail in some cases to efficiently produce thin metal stripsincluding fine grains.

An objective of the present invention is to provide an apparatus forproducing a thin metal strip that is capable of efficiently producing athin metal strip including fine grains.

Solution to Problem

A producing apparatus according to the present embodiment is anapparatus for producing a thin metal strip by a single roll stripcasting process. The producing apparatus includes a cooling roll, atundish, and a molten metal remover. The cooling roll includes an outerperipheral surface and is configured to cool and solidify molten metalon the outer peripheral surface while rotating. The tundish canaccommodate the molten metal and is configured to supply the moltenmetal onto the outer peripheral surface of the cooling roll. The moltenmetal remover is disposed downstream of the tundish in the rotatingdirection of the cooling roll with a gap provided between the moltenmetal remover and the outer peripheral surface of the cooling roll. Themolten metal remover is configured to remove a portion of a thickness ofthe molten metal on the outer peripheral surface of the cooling rollthat is larger than the width of the gap described above. As a result,the thickness of the molten metal on the outer peripheral surface of thecooling roll is cut down to the width of the gap between the outerperipheral surface of the cooling roll and the molten metal remover.

A method for producing a thin metal strip according to the presentembodiment is a method for producing a thin metal strip by a single rollstrip casting process using the producing apparatus described above. Theproducing method includes a supplying step, a rapid cooling step, and athickness adjustment step. In the supplying step, the molten metal inthe tundish is supplied onto the outer peripheral surface of the coolingroll. In the rapid cooling step, the molten metal on the outerperipheral surface is rapidly cooled with the cooling roll to be formedinto the thin metal strip. In the thickness adjustment step, a portionof a thickness of the molten metal on the outer peripheral surface ofthe cooling roll that is larger than the width of the gap describedabove is removed by the molten metal remover. As a result, the thicknessof the molten metal on the outer peripheral surface is cut down to thewidth of the gap between the outer peripheral surface of the coolingroll and the molten metal remover.

Advantageous Effects of Invention

Using the apparatus for producing a thin metal strip according to thepresent embodiment enables a thin metal strip including fine grains tobe produced efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an apparatus for producing a thinmetal strip according to the present embodiment.

FIG. 2 is a cross-sectional view of the vicinity of a front edge of amolten metal remover of the producing apparatus in an enlarging manner.

FIG. 3 is a diagram illustrating an attachment angle of the molten metalremover.

FIG. 4 is a cross-sectional view of a producing apparatus according toanother embodiment, which is different from that illustrated in FIG. 1to FIG. 3.

FIG. 5 is a cross-sectional view of a producing apparatus according toanother embodiment, which is different from that illustrated in FIG. 1to FIG. 4.

FIG. 6 is a diagram illustrating the cross sectional shape of a moltenmetal remover.

FIG. 7 is a diagram illustrating the cross sectional shape of a moltenmetal remover different from that illustrated in FIG. 6.

FIG. 8 is a diagram illustrating the cross sectional shape of a moltenmetal remover different from those illustrated in FIG. 6 and FIG. 7.

FIG. 9 is a picture of a cross section of a thin metal strip produced bya production method according to the present embodiment, taken under anelectron microscope (SEM).

FIG. 10 is a picture of a cross section of a thin metal strip producedwithout using the molten metal remover, taken under the electronmicroscope (SEM).

DESCRIPTION OF EMBODIMENTS

A producing apparatus according to the present embodiment is anapparatus for producing a thin metal strip by a single roll stripcasting process. The producing apparatus includes a cooling roll, atundish, and a molten metal remover. The cooling roll includes an outerperipheral surface and is configured to cool and solidify molten metalon the outer peripheral surface while rotating. The tundish canaccommodate the molten metal and is configured to supply the moltenmetal onto the outer peripheral surface of the cooling roll. The moltenmetal remover is disposed downstream of the tundish in the rotatingdirection of the cooling roll with a gap provided between the moltenmetal remover and the outer peripheral surface of the cooling roll. Themolten metal remover is configured to remove a portion of a thickness ofthe molten metal that is larger than the width of the gap describedabove (hereafter, also referred to as a surface portion). As a result,the thickness of the molten metal on the outer peripheral surface of thecooling roll is cut down to the width of the gap between the outerperipheral surface of the cooling roll and the molten metal remover.

The producing apparatus according to the present embodiment includes amolten metal remover. The molten metal remover is configured to be incontact with the molten metal when a free surface of the molten metal (asurface of the molten metal on a side on which the molten metal is notin contact with the cooling roll) in a liquid state or a semi-solidifiedstate. The molten metal remover is configured to remove the surfaceportion of the molten metal on the outer peripheral surface. As aresult, the thickness of the molten metal on the outer peripheralsurface of the cooling roll is cut down to the width of the gap betweenthe outer peripheral surface of the cooling roll and the molten metalremover. As a result, the molten metal on the outer peripheral surfaceof the cooling roll becomes thin. As the molten metal becomes thin, thecooling rate of the molten metal increases. As a result, grains in thethin metal strip become small. In other words, by using the stripcasting, it is possible to efficiently produce a thin metal stripincluding fine grains. In addition, by cutting down the width of thethickness of the molten metal to the width of the gap as describedabove, it is possible to perform rapid solidification without beingaffected not much by viscosity of the molten metal, wettability to theroll material, supply amount of the molten metal, and the like.

It is preferable that the width of a gap between the outer peripheralsurface of the cooling roll and the molten metal remover is smaller thanthe thickness of the molten metal on the outer peripheral surface of thecooling roll on an upstream side of the molten metal remover in therotating direction of the cooling roll.

In this case, the molten metal on the outer peripheral surface of thecooling roll becomes thinner. Therefore, the cooling rate of the moltenmetal becomes higher. As a result, the grains in the thin metal stripare more refined.

It is preferable that the tundish is disposed in the vicinity of theouter peripheral surface of the cooling roll and includes a supply endconfigured to guide the molten metal onto the outer peripheral surfaceof the cooling roll. In addition, the molten metal remover is disposedabove the supply end of the tundish.

In this case, the molten metal is cooled while being wound up by thecooling roll. Therefore, the time for which the molten metal is incontact with the outer peripheral surface of the cooling roll is long,and the cooling time of the molten metal is long. As a result, thegrains in the thin metal strip are more refined.

It is preferable that molten metal remover is disposed opposite to theouter peripheral surface of the cooling roll and includes a heatdissipation surface configured to be in contact with the molten metalpassing through the gap between the outer peripheral surface of thecooling roll and the molten metal remover.

In this case, the molten metal is subjected to heat dissipation from asurface in contact with the molten metal remover, as well as a surfacein contact with the cooling roll (hereafter, also referred to as asolidified portion). Therefore, the cooling rate of the molten metalbecomes high. As a result, the grains in the thin metal strip are morerefined.

A method for producing a thin metal strip according to the presentembodiment is a method for producing a thin metal strip by a single rollstrip casting process using the producing apparatus described above. Theproducing method includes a supplying step, a rapid cooling step, and athickness adjustment step. In the supplying step, the molten metal inthe tundish is supplied onto the outer peripheral surface of the coolingroll. In the rapid cooling step, the molten metal on the outerperipheral surface is rapidly cooled with the cooling roll to be formedinto the thin metal strip. In the thickness adjustment step, a portionof a thickness of the molten metal on the outer peripheral surface ofthe cooling roll that is larger than the width of the gap describedabove is removed by the molten metal remover. As a result, the thicknessof the molten metal on the outer peripheral surface is cut down to thewidth of the gap between the outer peripheral surface of the coolingroll and the molten metal remover.

The producing method according to the present embodiment includes thethickness adjustment step. Through the thickness adjustment step, themolten metal on the outer peripheral surface of the cooling roll becomesthin. Therefore, the cooling rate of the molten metal becomes high. As aresult, the grains in the thin metal strip are refined. In other words,by using the strip casting process, it is possible to efficientlyproduce a thin metal strip including fine grains.

The thin metal strip produced by the above production method of a thinmetal strip may contain a chemical composition that includes Cu and Sn,and may contain a phase having D0₃ structure in the Strukturberichtnotation. The powder obtained by pulverizing this thin metal strip canbe used as a negative electrode active material for a nonaqueouselectrolyte secondary battery, such as a lithium ion secondary battery.This negative electrode active material has excellent charge-dischargecapacity and capacity retention characteristics. A chemical compositionof the above thin metal strip consists of, for example, 10 to 20 at % or21 to 27 at % of Sn, with the balance being Cu and impurities. Thechemical composition of the above thin metal strip may further containone or more selected from the group consisting of Ti, V, Cr, Mn, Fe, Co,Ni, Zn, Al, Si, B, and C in place of a part of Cu.

With the producing method according to the present embodiment, in caseof the above chemical composition, the ratio of the phase having D0₃structure (hereinafter referred to as D0₃ phase) can be increased.Therefore, battery characteristics (capacity retention rate etc.) areincreased.

The present embodiment will be described below in detail with referenceto the accompanying drawings. The same or equivalent elements will bedenoted by the same reference numerals, and the description thereof willnot be repeated.

[Producing Apparatus]

FIG. 1 is a cross-sectional view of an example of an apparatus forproducing a thin metal strip according to the present embodiment. Aproducing apparatus 1 includes a cooling roll 2, a tundish 4, and amolten metal remover 5.

[Cooling Roll]

The cooling roll 2 has an outer peripheral surface and is configured tocool and solidify molten metal 3 on the outer peripheral surface whilerotating. The cooling roll 2 includes a column-shaped barrel portion anda shaft portion not illustrated. The barrel portion includes the outerperipheral surface described above. The shaft portion is disposed at acentral axis position of the barrel portion and attached to a drivingsource not illustrated. The cooling roll 2 is configured to be rotatedabout a central axis 9 of the cooling roll 2 by the driving source.

The starting material of the cooling roll 2 is preferably a materialhaving a high hardness and a high thermal conductivity. The startingmaterial of the cooling roll 2 is, for example, one selected from thegroup consisting of copper and copper alloys. The starting material ofthe cooling roll 2 is preferably copper. The cooling roll 2 may furtherinclude a coating on its surface. This inclusion of the coatingincreases the hardness of the cooling roll 2. Therefore, it isadvantageous, particularly in mass production. The coating is, forexample, one or two selected from the group consisting of platingcoating and cermet coating. The plating coating is, for example, one ortwo selected from the group consisting of chromium plating and nickelplating. The cermet coating contains, for example, one, or two or moreselected from the group consisting of tungsten (W), cobalt (Co),titanium (Ti), chromium (Cr), nickel (Ni), silicon (Si), aluminum (Al),boron (B), and carbides, nitrides, and carbo-nitrides of these elements.It is preferable that the outer layer of the cooling roll 2 is made ofcopper, and the cooling roll 2 further includes a chromium platingcoating on its surface.

Reference character X illustrated in FIG. 1 denotes the rotatingdirection of the cooling roll 2. In producing a thin metal strip 6, thecooling roll 2 rotates in a given direction X. By this rotation, in FIG.1, the molten metal 3 coming into contact with the cooling roll 2 ispartially solidified on the outer peripheral surface of the cooling roll2 and moves with the rotation of the cooling roll 2.

The cooling roll 2 includes a cooling zone that lies downstream of thetundish 4 to be described later in the rotating direction of the coolingroll 2 but does not reach the molten metal remover 5 to be describedlater. In the cooling zone, the molten metal 3 supplied onto the outerperipheral surface of the cooling roll 2 has a free surface. Therefore,rapid cooling is enabled. If the molten metal 3 has no free surface,that is, if a solidified portion of the molten metal 3 is covered withanother portion of molten metal 3, the solidified portion cannot besubjected to sufficient heat dissipation. This is because heat iscontinuously added to the solidified portion from the molten metal 3lying on the solidified portion. In the cooling zone, the molten metal 3is made to have the free surface by being supplied onto the outerperipheral surface of the cooling roll 2. Therefore, the solidifiedportion can be subjected to sufficient heat dissipation, which enablesthe rapid cooling. As a result, it is possible to obtain the thin metalstrip 6 including more refined grains.

The roll peripheral speed of the cooling roll 2 is set as appropriate inconsideration of the cooling rate and the efficiency of manufacturing ofthe molten metal 3. The higher the roll peripheral speed is, the moreeasily the thin metal strip 6 peels off from the outer peripheralsurface of the cooling roll 2. Therefore, the lower limit of the rollperipheral speed is preferably 50 m/min, more preferably 80 m/min, andstill more preferably 120 m/min. The upper limit of the roll peripheralspeed is not particularly limited but, for example, 500 m/min inconsideration of a plant capacity. The roll peripheral speed can bedetermined from the diameter and the number of revolutions of the roll.

The inside of the cooling roll 2 may be filled with solvent for the heatdissipation. It is thereby possible to subject the molten metal 3 to theheat dissipation efficiently. The solvent is, for example, one, or twoor more selected from the group consisting of water, organic solvent,and oil. The solvent may stay inside the cooling roll 2 or may becirculated through the outside.

[Tundish]

The tundish 4 can accommodate the molten metal 3 and is configured tosupply the molten metal 3 onto the outer peripheral surface of thecooling roll 2.

In the present embodiment, the tundish 4 may always be heated. In thiscase, the melted state of the molten metal 3 having a high fusing pointcan be maintained. As a result, the molten metal 3 can be removedremaining in the melted state, with the molten metal remover 5 to bedescribed later. A heating temperature is not particularly limited aslong as the heating temperature is equal to or higher than the liquidustemperature of a raw material. In a case of producing a Si alloy, theheating temperature is, for example, 1200° C. or more, and a morepreferable heating temperature is 1500° C. or more. In a case ofproducing an alloy material for a magnet, the heating temperature is,for example, 1000° C. or more.

The shape of the tundish 4 is not particularly limited as long as themolten metal 3 can be supplied onto the outer peripheral surface of thecooling roll 2. As shown in FIG. 1, the shape of the tundish 4 may be abox-like shape with an open top, or may be other shapes.

The tundish 4 includes a supply end 7 for guiding the molten metal 3 onthe outer peripheral surface of the cooling roll 2. The molten metal 3is supplied from a crucible (not shown) to the tundish 4, and thensupplied to the outer peripheral surface of the cooling roll 2 throughthe supply end 7. The shape of the supply end 7 is not particularlylimited. The cross section of the supply end 7 may be rectangular asshown in FIG. 1 or it may be inclined. Alternatively, the supply end 7may be in the form of a nozzle.

Preferably, the tundish 4 is disposed in the vicinity of the outerperipheral surface of the cooling roll 2. Thereby, the molten metal 3can be stably supplied onto the outer peripheral surface of the coolingroll 2. The gap between the tundish 4 and the cooling roll 2 isappropriately set within a range where the molten metal 3 does not leak.

The material of the tundish 4 is preferably refractory. The tundish 4 ismade of, for example, one or more selected from the group consisting ofaluminum oxide (Al₂O₃), silicon monoxide (SiO), silicon dioxide (SiO₂),chromium oxide (Cr₂O₃), magnesium oxide (MgO), titanium oxide (TiO₂),aluminum titanate (Al₂TiO₅), And zirconium oxide (ZrO₂).

[Molten Metal Remover]

The molten metal remover 5 is a member that extends along the shaftdirection of the cooling roll 2. An example of the molten metal remover5 is a plate-shaped member that is disposed in parallel to the shaftdirection of the cooling roll 2, as illustrated in FIG. 1. The moltenmetal remover 5 is disposed downstream of the tundish 4 in the rotatingdirection of the cooling roll 2 with a gap provided between the moltenmetal remover 5 and the outer peripheral surface of the cooling roll 2.The molten metal remover 5 consists a main body 51 and a front edgeportion 50 that is disposed opposite to the outer peripheral surface ofthe cooling roll 2. The shape of the front edge portion 50 is notparticularly limited.

FIG. 2 is a cross-sectional view illustrating the vicinity of the frontedge portion 50 of the molten metal remover 5 included in the producingapparatus 1 (a region surrounded by a broken line in FIG. 1) in anenlarging manner. Referring to FIG. 2, the molten metal remover 5 isdisposed with a gap A between the molten metal remover 5 and the outerperipheral surface of the cooling roll 2. The molten metal remover 5 isconfigured to cut down the thickness of the molten metal 3 on the outerperipheral surface of the cooling roll 2 to the width of the gap Abetween the outer peripheral surface of the cooling roll 2 and themolten metal remover 5. Specifically, there is a case where the moltenmetal 3 lying upstream of the molten metal remover 5 in the rotatingdirection of the cooling roll 2 has a large thickness as compared withthe width of the gap A. In this case, an amount of molten metal 3corresponding to a thickness by which the thickness of the molten metal3 is more than the width of the gap A is removed by the molten metalremover 5. By this removal, the thickness of the molten metal 3 isreduced to the width of the gap A. The reduced thickness of the moltenmetal 3 makes the cooling rate of the molten metal 3 higher. As aresult, the grains in the thin metal strip 6 are refined.

The width of the gap A is preferably smaller than a thickness B of themolten metal 3 on the outer peripheral surface on an upstream side ofthe molten metal remover 5 in the rotating direction of the cooling roll2. In this case, the molten metal 3 on the outer peripheral surface ofthe cooling roll 2 becomes thinner. Therefore, the cooling rate of themolten metal 3 becomes higher. As a result, the grains in the thin metalstrip 6 are more refined.

The width of the gap A between the outer peripheral surface of thecooling roll 2 and the molten metal remover 5 is a shortest distancebetween the molten metal remover 5 and the outer peripheral surface ofthe cooling roll 2. The width of the gap A is set as appropriate inaccordance with a target cooling rate and a target efficiency ofmanufacturing. The smaller the width of the gap A, the thinner themolten metal 3 subjected to thickness adjustment. Therefore, the coolingrate of the molten metal 3 becomes higher. As a result, the grains inthe thin metal strip 6 are more easily refined. Consequently, the upperlimit of the gap A is preferably 400 more preferably 250 μm, still morepreferably 100 μm, even still more preferably 50 μm, even still morepreferably 30 μm. In a case where the cooling roll 2 includes chromiumplating and nickel plating on its surface, the cooling rate is slow ascompared with a case where the surface of the cooling roll 2 is made ofcopper. Therefore, in this case, the gap A is preferably narrowed. Thelower limit of the gap A is not particularly limited but, for exampleto, 10 μm.

Of the outer peripheral surface of the cooling roll 2, the distancebetween a location where the molten metal 3 is supplied from the tundish4 and a location where the molten metal remover 5 is disposed is set asappropriate. The molten metal remover 5 may be disposed in a regionwhere the free surface of the molten metal 3 (a surface of the moltenmetal 3 on a side on which the molten metal 3 is not in contact with thecooling roll 2) is in contact with the molten metal remover 5 in theliquid state or the semi-solidified state.

FIG. 3 is a diagram illustrating an attachment angle of the molten metalremover 5. Referring to FIG. 3, for example, the molten metal remover 5is disposed such that an angle θ formed by a plane PL 1 including thecentral axis 9 of the cooling roll 2 and a supply end 7, and a plane PL2including the central axis 9 of the cooling roll 2 and the front edgeportion 50 of the molten metal remover 5 is constant (Hereafter, thisangle θ will be referred to as an attachment angle θ.). The attachmentangle θ can be set as appropriate. The upper limit of the attachmentangle θ is, for example, 45°. The upper limit of the attachment angle θis preferably 30°. The lower limit of the attachment angle θ is notparticularly limited but is preferably within such a range that does notcause the molten metal remover 5 not to directly come into contact withthe molten metal 3 on the tundish 4.

Referring to FIG. 1 to FIG. 3, it is preferable that the molten metalremover 5 includes a heat dissipation surface 8. The heat dissipationsurface 8 is disposed opposite to the outer peripheral surface of thecooling roll 2. The heat dissipation surface 8 is configured to comeinto contact with the molten metal 3 passing through a gap between theouter peripheral surface of the cooling roll 2 and the molten metalremover 5.

The starting material of the molten metal remover 5 is preferably arefractory material. The molten metal remover 5 contains, for example,one, or two or more selected from the group consisting of aluminum oxide(Al₂O₃), silicon monoxide (SiO), silicon dioxide (SiO₂), chromium oxide(Cr₂O₃), magnesium oxide (MgO), titanium oxide (TiO₂), aluminum titanate(Al₂TiO₅), and zirconium oxide (ZrO₂). It is preferable that the moltenmetal remover 5 contains one, or two or more selected from the groupconsisting of aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), aluminumtitanate (Al₂TiO₅), and magnesium oxide (MgO).

In the producing apparatus 1 described above, the molten metal remover 5removes a surface portion of the molten metal 3 on the outer peripheralsurface of the cooling roll 2. The surface portion of the molten metal 3means a portion of a thickness of the molten metal 3 on the outerperipheral surface of the cooling roll 2 that is larger than the widthof the gap A between the outer peripheral surface of the cooling roll 2and the molten metal remover 5. This cuts down the thickness of themolten metal 3 on the outer peripheral surface of the cooling roll 2. Asa result, the molten metal 3 on the outer peripheral surface of thecooling roll 2 becomes thin. The reduction of the molten metal 3 inthickness makes the cooling rate of the molten metal 3 higher.Therefore, by producing a thin metal strip using the producing apparatus1, it is possible to obtain the thin metal strip 6 including morerefined grains.

The apparatus for producing a thin metal strip according to the presentembodiment is not limited to the producing apparatus 1 described above.

In the producing apparatus 1 illustrated in FIG. 1, the molten metal 3is supplied from a lateral side of the cooling roll 2. However, themolten metal 3 can be supplied above the cooling roll 2.

FIG. 4 is a cross-sectional view of a producing apparatus 10 accordingto another embodiment, which is different from that illustrated in FIG.1 to FIG. 3. Referring to FIG. 4, the tundish 4 and the supply end 7 aredisposed above the cooling roll 2. The molten metal remover 5 isdisposed below the supply end 7. The rest of the configuration of theproducing apparatus 10 is the same as that of the producing apparatus 1.In the producing apparatus 10, the molten metal 3 is supplied from abovethe cooling roll 2 onto the outer peripheral surface of the cooling roll2. The thickness of the molten metal 3 supplied onto the outerperipheral surface of the cooling roll 2 is cut down by the molten metalremover 5 as with the producing apparatus 1. As a result, the thicknessof the molten metal 3 on the outer peripheral surface of the coolingroll 2 is reduced to the width of the gap A between the outer peripheralsurface of the cooling roll 2 and the molten metal remover 5.

In the producing apparatus 10, the molten metal 3 is cooled whiledescending from the top of the cooling roll 2 along the outer peripheralsurface of the cooling roll 2. Meanwhile, in the producing apparatus 1illustrated in FIG. 1, the molten metal 3 is supplied from a lateralside of the cooling roll 2 in the same direction as the rotatingdirection of the cooling roll 2. In addition, the molten metal 3 iswound up by the cooling roll 2 to reach the top of the cooling roll 2and then descends on the outer peripheral surface of the cooling roll 2to be cooled. For that reason, in a case of using the producingapparatus 1, the time for which the molten metal 3 is in contact withthe outer peripheral surface of the cooling roll 2 is long as comparedwith the producing apparatus 10. As a result, the cooling time of themolten metal 3 is long. In this case, the grains in the thin metal strip6 are more refined. Consequently, the producing apparatus 1 illustratedin FIG. 1, that is, disposing the molten metal remover 5 above thesupply end 7 of the tundish 4 is preferable.

The number of molten metal removers 5 to be disposed may be one asillustrated in FIG. 1 to FIG. 4, or a plurality of molten metal removers5 may be disposed continuously in the rotating direction of the coolingroll 2. In a case where a plurality of molten metal removers 5 aredisposed, the molten metal remover(s) 5 disposed on a downstream side inthe rotating direction of the cooling roll 2 are disposed to be closerto the cooling roll 2 than the molten metal remover(s) 5 disposed on anupstream side in the rotating direction of the cooling roll 2. Inaddition, a molten metal remover 5 at a most downstream position in therotating direction of the cooling roll 2 is disposed such that a gap Abetween the molten metal remover 5 and the outer peripheral surface ofthe cooling roll 2 becomes the narrowest. Disposing a plurality ofmolten metal removers 5 enables stepwise removal of the molten metal 3.In this case, a load applied to one molten metal remover 5 is lower. Inthis case, moreover, precise control of the thickness of the moltenmetal 3 is facilitated.

The molten metal remover 5 may be disposed in a direction along a normalline of the cooling roll 2 as illustrated in FIG. 1 to FIG. 4 or may bedisposed in a direction different from a normal line of the cooling roll2 as illustrated in FIG. 5. In FIG. 5, the molten metal remover 5 isdisposed such as to incline from a normal direction of the cooling roll2 toward the rotating direction of the cooling roll 2. In this case, itis easy to remove a portion of the molten metal 3 on the outerperipheral surface of the cooling roll 2 that is higher than the widthof the gap A. In other words, it is easy to cut down the thickness ofthe molten metal 3 on the outer peripheral surface of the cooling roll2. In FIG. 5, moreover, the molten metal remover 5 is configured to havea cross sectional shape different from that illustrated in FIG. 1 toFIG. 4, which will be described later. In this case, the removal of themolten metal 3 can be performed even more efficiently. The direction ofthe molten metal remover 5 is set as appropriate such that the cut-downof the thickness of the molten metal 3 is easy.

The cross sectional shape of the front edge portion 50 of the moltenmetal remover 5 (an edge of the molten metal remover 5 to be in contactwith the molten metal 3) in a cross section perpendicular to the shaftof the roll may be a rectangle as illustrated in FIG. 1 to FIG. 4 or maybe in another shape. Another shape may be, for example, a triangle asillustrated in FIG. 6. Alternatively, as illustrated in FIG. 5 and FIG.7, the front edge portion 50 of the molten metal remover 5 may be in ashape in which the width of a gap between the front edge portion 50 ofthe molten metal remover 5 on an entrance side for the molten metal 3and the outer peripheral surface of the cooling roll 2 is different fromthe width of a gap between the front edge portion 50 of the molten metalremover 5 on an exit side for the molten metal 3 and the outerperipheral surface of the cooling roll 2. The cross sectional shape ofthe front edge portion 50 of the molten metal remover 5 is set asappropriate such that the thickness of the molten metal 3 is easily cutdown.

[Producing Method]

A method for producing the thin metal strip 6 according to the presentembodiment is a producing method using the producing apparatus 1 or 10described above. The producing method includes a supplying step, a rapidcooling step, and a thickness adjustment step.

First, the molten metal 3 is prepared. The composition of the moltenmetal 3 is set as appropriate in accordance with an intended compositionof the thin metal strip 6. For example, in a case of producing Si alloy,the molten metal 3 contains, for example, one, or two or more selectedfrom the group consisting of silicon (Si), titanium (Ti), chromium (Cr),vanadium (vanadium), manganese (Mn), iron (Fe), cobalt (Co), nickel(Ni), zinc (Zn), aluminum (Al), copper (Cu), and tin (Sn), with thebalance being impurities. In the case of producing a metal ribbon for anegative electrode active material used in a lithium secondary batteryor the like, it is preferable to produce the molten metal 3 so as toobtain a metal ribbon having the chemical composition described below.Alternatively, in a case of producing an alloy material for a neodymiummagnet, the molten metal 3 consists, for example, neodymium (Nd), boron(B), and iron (Fe), with the balance being impurities. The molten metal3 is produced by heating a raw material having the chemical compositiondescribed above to the fusing point of the raw material or higher.

By putting the raw material having the chemical composition describedabove in a crucible and heating the raw material, the molten metal 3 isproduced. Examples of the method of the heating include high-frequencyinduction heating, arc heating, plasma arc heating, electric resistanceheating, and electron beam heating. A heating temperature is notparticularly limited as long as the heating temperature is equal to orhigher than the liquidus temperature of the raw material. In a case ofproducing a Si alloy, the heating temperature is, for example, 1200° C.or more, more preferably 1500° C. or more. In a case of producing analloy material for a magnet, the heating temperature is, for example,1000° C. or more.

[Supplying Step]

In the supplying step, the molten metal 3 in the tundish 4 is suppliedonto the outer peripheral surface of the cooling roll 2. First, themolten metal 3 is supplied from the crucible to the tundish 4. Thesupply of the molten metal 3 from the crucible to the tundish 4 may bemade by tilting the crucible to pour the molten metal 3 directly.Alternatively, a nozzle or the like may be used to supply the moltenmetal 3 from the crucible to the tundish 4. Subsequently, from thesupply end 7 of the tundish 4, the molten metal 3 is supplied onto theouter peripheral surface of the cooling roll 2. The cooling roll 2rotates, as described above, about the central axis 9 of the coolingroll 2 at a given speed. When the molten metal 3 supplied from thetundish 4 comes into contact with the outer peripheral surface of thecooling roll 2, the molten metal 3 is partially solidified to betransferred to the cooling roll 2. The molten metal 3 moves with therotation of the cooling roll 2. At this point, a surface of the moltenmetal 3 not in contact with the outer peripheral surface of the coolingroll 2 (free surface) is in a liquid state or a semi-solidified state.

In the supplying step, the tundish 4 may always be heated. In this case,the melted state of the molten metal 3 having a high fusing point can bemaintained. Therefore, the molten metal 3 can be removed by the moltenmetal remover 5 while being in the melted state. A heating temperatureis not particularly limited as long as the heating temperature is equalto or higher than the liquidus temperature of the raw material. In acase of producing a Si alloy, the heating temperature is, for example,1200° C. or more, and a more preferable heating temperature is 1500° C.or more. In a case of producing an alloy material for a magnet, theheating temperature is, for example, 1000° C. or more.

[Rapid Cooling Step]

In the rapid cooling step, the molten metal 3 on the outer peripheralsurface is rapidly cooled with the cooling roll 2 to be formed into thethin metal strip 6. The rapid cooling step is started when the moltenmetal 3 is supplied onto the outer peripheral surface of the coolingroll 2 in the supplying step described above. In the rapid coolingprocess, the molten metal 3 is cooled from a solidified portion.

In the rapid cooling step, the cooling roll 2 includes a cooling zonethat lies downstream of the tundish 4 in the rotating direction of thecooling roll 2 but does not reach the molten metal remover 5. In thecooling zone, the molten metal 3 supplied onto the outer peripheralsurface of the cooling roll 2 includes a free surface. Therefore, rapidcooling is enabled. If the molten metal 3 has no free surface, that is,if the solidified portion is covered with another portion of moltenmetal 3, the solidified portion cannot be subjected to sufficient heatdissipation. This is because heat is continuously added to thesolidified portion from the molten metal 3 lying on the solidifiedportion. In the cooling zone, the molten metal 3 is made to have thefree surface by being supplied onto the outer peripheral surface of thecooling roll 2. Therefore, the solidified portion can be subjected tosufficient heat dissipation, which enables the rapid cooling. As aresult, the thin metal strip 6 including more refined grains can beproduced.

[Thickness Adjustment Step]

In the thickness adjustment step, the thickness of the molten metal 3 onthe outer peripheral surface of the cooling roll 2 is cut down by themolten metal remover 5, in the middle of the rapid cooling step, to thewidth of the gap A between the outer peripheral surface of the coolingroll 2 and the molten metal remover 5. Immediately after supplied ontothe outer peripheral surface of the cooling roll 2, the molten metal 3is not solidified as a whole but gradually solidified from a solidifiedportion. The free surface of the molten metal 3 comes into contact withthe molten metal remover 5, in a liquid state or a semi-solidifiedstate. The hardness of the molten metal 3 in the liquid state or thesemi-solidified state is low. Therefore, when the thickness of themolten metal 3 is larger than the width of the gap A, the free surfaceof the molten metal 3 in the liquid state or the semi-solidified stateis blocked or removed. The molten metal 3 thereby becomes thin. As themolten metal 3 is thinner, the cooling rate of the molten metal 3increases. As a result, the thin metal strip 6 including more refinedgrains can be produced.

The disposition of the heat dissipation surface 8 enables the moltenmetal 3 to be subjected to heat dissipation from the heat dissipationsurface 8 as well as the solidified portion. In this case, the coolingrate of the molten metal 3 becomes high. The area and shape of the heatdissipation surface 8 are set as appropriate. For example, asillustrated in FIG. 8, by forming the front edge portion 50 of themolten metal remover 5 into an L shape, the area of the heat dissipationsurface 8 can be increased. In this case, the cooling rate of the moltenmetal 3 can be made higher.

The molten metal 3 reduced in thickness through the thickness adjustmentstep is subsequently cooled on the cooling roll 2. At this point, themolten metal 3 is thin. Therefore, the cooling rate is remarkably high.As a result, grains in the thin metal strip 6 are fine. The entiremolten metal 3 is solidified into the thin metal strip 6. The thin metalstrip 6 is separated from the outer peripheral surface of the coolingroll 2 and collected. Through the above steps, the thin metal strip 6according to the present embodiment can be produced.

[Production of Thin Metal Strip for Negative Electrode Active Material]

As a negative electrode active material made of a metal, it ispreferable that the ratio of a phase having D0₃ structure inStrukturbericht notation (hereinafter also referred to as D0₃ phase) islarge. When pulverizing the thin metal strip and using it as a negativeelectrode active material (powder) for a lithium secondary battery, theD0₃ phase acts as a host for occlusion and release a lithium. Therefore,the greater the ratio of D0₃ phase in the metal strip is, the better theelectric capacity and the cycle life of a battery are.

In the manufacturing method of this embodiment, it is easy to generateD0₃ phase. Therefore, it is suitable for the production of a metalribbon for a negative electrode active material used in a lithiumsecondary battery.

A preferable chemical composition of the thin metal strip as a negativeelectrode active material is Sn, with the balance being Cu andimpurities. More preferably, the chemical composition of the thin metalstrip contains 10 to 20 at % or 21 to 27 at % of Sn, with the balancebeing Cu and impurities. In the chemical composition of the thin metalstrip, the more preferable Sn content is 13 to 16 at %, 18.5 to 20 at %,or 21 to 27 at %.

The chemical composition may contain 10 to 20 at % or 21 to 27 at % ofSn, and one or more selected from the group consisting of Ti, V, Cr, Mn,Fe, Co, Ni, Zn, Al, Si, B, and C, with the balance being Cu andimpurities. More specifically, the above chemical composition maycontain: Sn: 10 to 20 at % or 21 to 27 at % of Sn, and one or moreselected from the group consisting of Ti: 9.0 at % or less, V: 49.0 at %or less, Cr: 49.0 at % or less, Mn: 9.0 at % or less, Fe: 49.0 at % orless, Co: 49.0 at % or less, Ni: 9.0 at % or less, Zn: 29.0 at % orless, Al: 49.0 at % or less, Si: 49.0 at % or less, B: 5.0 at % or less,and C: 5.0 at % or less, with the balance being Cu and impurities.

EXAMPLES Example I

Using a producing apparatus described in the following Example 1 toExample 3, thin metal strips made of Si alloy were produced. A rawmaterial contained nickel (Ni), titanium (Ti), and silicon (Si). Thecomposition of the raw material was, in mass ratio, Ni:Ti:Si=25:17:58.One kilogram of the raw material in a mixed state was heated to 1450° C.to be produced into molten metal. The molten metal was supplied from thetundish onto the cooling roll. The cooling roll was one the outerperipheral surface of which is covered with copper and the inside ofwhich is cooled by water. The cooling roll had a diameter of 20 cm and awidth of 18 cm. The peripheral speed of the roll was 120 m/min. The thinmetal strips made of Si alloy obtained in Example 1 to Example 3 werecut, and cross sections were observed under a scanning electronmicroscope (SEM).

Example 1

In Example 1, the producing apparatus according to the presentembodiment was used to produce a thin metal strip made of Si alloy. Inother words, the thin metal strip made of Si alloy was produced usingthe molten metal remover. The molten metal remover was a flat aluminaplate having a thickness of 3 mm. The width of the gap between themolten metal remover and the outer peripheral surface of the coolingroll was 80 μm.

Example 2

In Example 2, a thin metal strip made of Si alloy was produced using theproducing apparatus according to the present embodiment from which themolten metal remover was detached. In other words, the thin metal stripmade of Si alloy was produced without using the molten metal remover.

Example 3

In Example 3, a thin metal strip made of Si alloy was produced under thesame conditions as those of Example 1 except that a producing apparatuswith no cooling zone on the cooling roll in a region between the tundishand the molten metal remover was used. In other words, without the freesurface, the molten metal was supplied to the molten metal remover.

Result of Evaluation Example 1

FIG. 9 is a picture of a cross section of the thin metal strip producedby the producing method according to the present embodiment (with themolten metal remover), taken under the electron microscope (SEM). Thethin metal strip produced by the method according to the presentembodiment had an average coating thickness of 80 μm. In addition, thesize of a grain in a Si phase of the thin metal strip produced by themethod according to the present embodiment (equivalent to the width of agray portion in FIG. 9) was not more than 2 μm.

Example 2

FIG. 10 is a picture of a cross section of the thin metal strip producedby a conventional method (without the molten metal remover), taken underthe electron microscope (SEM). The thin metal strip produced by theconventional method had an average coating thickness of 440 μm. Inaddition, the size of a grain in a Si phase of the thin metal stripproduced by the conventional method (equivalent to the width of a grayportion in FIG. 10) was 20 to 30 μm.

Example 3

In Example 3, in which the production was made by removing the moltenmetal without the free surface with the molten metal remover, the sizeof a grain in a Si phase of the thin metal strip was 10 to 15 μm.

From the above, the method according to the present embodiment providesa thin metal strip with finer crystal grain than the conventionalmethod.

Example II

Metallic ribbons were produced under various producing conditions. Eachof the thin metal strip had a chemical composition, containing 20.0 at %of Sn and 8.0 at % of Si, with the balance being Cu and impurities. Theratio (mass %) of D0₃ phase (phase having D0₃ structure) in the producedthin metal strip was determined.

[Experimental Method]

Initially, molten metals with the chemical composition of test numbers 1to 8 shown in Table 1 were prepared.

TABLE 1 Gap between Cooling Blade Roll Member D0₃Fase Peripheral andRatio in Melting Speed Cooling Cooling Thin Test Temperature (m/ RollBlade Roll Strip No. Chemical Composition of Alloy (° C.) minute)Surface Member (μm) (mass %) Note 1 Cu—20.0at % Sn—8.0at % Si 1250 120Cu Installed 109  77.8 Inventive Example 2 Cu—20.0at % Sn—8.0at % Si1250 360 Cu Installed 89 78.1 Inventive Example 3 Cu—20.0at % Sn—8.0at %Si 1250 360 Cr Installed 89 44.9 Inventive plated Example 4 Cu—20.0at %Sn—8.0at % Si 1250 120 Cr Not — 6.9 Comparative plated installed Example5 Cu—20.0at % Sn—7.0at % Si—1.0at % Ti 1250 360 Cu Installed 89 70.2Inventive Example 6 Cu—20.0at % Sn—7.0at % Si—1.0at % V 1250 360 CuInstalled 89 71.6 Inventive Example 7 Cu—20.0at % Sn—6.0at % Si—1.0at %Al—1.0at % Zn 1250 360 Cu Installed 89 72.5 Inventive Example 8Cu—20.0at % Sn—6.0at % Si—1.0at % Cr—1.0at % Ni 1250 360 Cu Installed 8968.3 Inventive Example

The composition of raw material of the molten metal wasCu:Sn:Si=63.8:33.1:3.1 by mass ratio at each test number. 1 kg of theraw material was heated to 1250° C. to produce molten metal.

Using the molten metal described above, in test numbers 1 to 3 and 5 to8, thin metal strips were produced by the production method (with ablade member) of this embodiment. In test number 4, a thin metal stripwas produced by a conventional manufacturing method (without a blademember).

Specifically, molten metal of each test number was provided onto thecooling roll from the tundish. The composition of the coating film onthe surface of the cooling roll used was as shown in Table 1. That is,in test numbers. 1 and 2, the surface of the cooling roll was Cu, and intest numbers 3 and 4, the surface of the cooling roll was a Cr platingfilm. The interior of the cooling roll was cooled with water. Thediameter of the cooling roll was 20 cm, and the width was 18 cm.

With the peripheral velocity of the cooling roll shown in Table 1,molten metal was provided onto the cooling role at the temperature shownin Table 1 to produce a thin metal strip. At this time, in test numbers.1 to 3, a blade member was used. The material of the blade member wasalumina and the blade member was a flat plate having a thickness of 3mm. The gap between the blade member and the cooling roll of each testnumbers 1 to 3 was as shown in Table 1. In test number 4, no blademember was used.

The ratio occupied by D0₃ phase in the produced thin metal strips ofeach test numbers 1 to 8 was determined by the following method.

X-ray diffraction measurement was conducted on the thin metal strips andmeasurement data of the X-ray diffraction profile was obtained.Specifically, an X-ray diffraction profile of the thin metal strip wasobtained, using a SmartLab (rotor target maximum output 9 KW; 45 kV-200mA) manufactured by Rigaku Corporation. Based on the obtained X-raydiffraction profile (measured data), the crystal structure in the thinmetal strip was analyzed by the Rietveld method. The X-ray diffractionapparatus and measurement conditions are described below.

(X-Ray Diffraction Apparatus and Measurement Conditions)

-   -   Apparatus: SmartLab manufactured by Rigaku Corporation    -   X-ray tube: Cu—Kα ray    -   X-ray output: 40 kV, 200 mA    -   Incident monochrometer: Johannson type crystal (which filters        out Cu-Kα₂ ray and Cu—Kβ ray)    -   Optical system: Bragg-Brentano geometry    -   Incident parallel slit: 5.0 degrees    -   Incident slit: ½ degrees    -   Length limiting slit: 10.0 mm    -   Receiving slit 1: 8.0 mm    -   Receiving slit 2: 13.0 mm    -   Receiving parallel slit: 5.0 degrees    -   Goniometer: SmartLab goniometer    -   X-ray source—mirror distance: 90.0 mm    -   X-ray source—selection slit distance: 114.0 mm    -   X-ray source—sample distance: 300.0 mm    -   Sample—receiving slit 1 distance: 187.0 mm    -   Sample—receiving slit 2 distance: 300.0 mm    -   Receiving slit 1—receiving slit 2 distance: 113.0 mm    -   Sample—detector distance: 331.0 mm    -   Detector: D/Tex Ultra    -   Scan range: 10 to 120 degrees    -   Scan step: 0.02 degrees    -   Scan mode: Continuous scan    -   Scanning speed: 0.1 degrees/min

The crystal structure of D0₃ phase is cubic, and in terms ofclassification of a space group, No. 225(Fm-3m) of International Table(Volume-A).

Accordingly, with the structure model of this space group number beingas the initial structure model of Rietveld analysis, a calculated valueof diffraction profile (hereinafter, referred to as a calculatedprofile) of each thin metal strip was found by Rietveld method.Rietan-2000 (program name) was used for Rietveld analysis.

From the each diffraction peaks at the powder X-ray diffraction profileand the Rietveld method, the existence of D0₃ phase in the thin metalstrips was confirmed. When the D0₃ phase was present, the ratio (mass %)of the D0₃ phase was determined.

[Result of Evaluation]

The ratio of D0₃ phase is shown in Table 1. Referring to Table 1, theratio of D0₃ phase in the thin metal strips of test numbers 1 to 3 and 5to 8 produced by the product method (with a blade member) of the presentembodiment was higher than the ration of D0₃ phase in the thin metalstrip of test number 4 produced by the conventional production method).

Furthermore, when comparing test numbers 1 to 3 and 5 to 8, when thesurface of the cooling roll was Cu, the ratio of D0₃ phase was higher ascompared with the case of the Cr plating film on the surface of thecooling roll. It is thought that Cu had a higher heat transfer propertythan the Cr plating film and it was easy to quench the molten metal.

The embodiment according to the present invention has been describedabove. However, the aforementioned embodiment is merely an example forpracticing the present invention. Therefore, the present invention isnot limited to the aforementioned embodiment, and the aforementionedembodiment can be modified and implemented as appropriate withoutdeparting from the scope of the present invention.

REFERENCE SIGNS LIST

-   1, 10 producing apparatus-   2 cooling roll-   3 molten metal-   4 tundish-   5 molten metal remover-   6 thin metal strip-   7 supply end-   8 heat dissipation surface

1. An apparatus for producing a thin metal strip by a single roll stripcasting process, the apparatus comprising: a cooling roll including anouter peripheral surface and configured to cool and solidify moltenmetal on the outer peripheral surface while rotating; a tundish capableof accommodating the molten metal and configured to supply the moltenmetal onto the outer peripheral surface; and a molten metal removerdisposed downstream of the tundish in a rotating direction of thecooling roll with a gap between the molten metal remover and the outerperipheral surface, and configured to remove a portion of a thickness ofthe molten metal on the outer peripheral surface that is larger than awidth of the gap to cut down the thickness of the molten metal to thewidth of the gap.
 2. The apparatus for producing a thin metal stripaccording to claim 1, wherein the width of the gap is smaller than athickness of the molten metal on the outer peripheral surface on anupstream side of the molten metal remover in the rotating direction. 3.The apparatus for producing a thin metal strip according to claim 1,wherein the tundish is disposed in a vicinity of the outer peripheralsurface and includes a supply end configured to guide the molten metalonto the outer peripheral surface, and the molten metal remover isdisposed above the supply end. 4-5. (canceled)
 6. The apparatus forproducing a thin metal strip according to claim 2, wherein the tundishis disposed in a vicinity of the outer peripheral surface and includes asupply end configured to guide the molten metal onto the outerperipheral surface, and the molten metal remover is disposed above thesupply end.
 7. The apparatus for producing a thin metal strip accordingto claim 1, wherein the molten metal remover is disposed opposite to theouter peripheral surface and includes a heat dissipation surface to bein contact with the molten metal passing through the gap.
 8. Theapparatus for producing a thin metal strip according to claim 2, whereinthe molten metal remover is disposed opposite to the outer peripheralsurface and includes a heat dissipation surface to be in contact withthe molten metal passing through the gap.
 9. The apparatus for producinga thin metal strip according to claim 3, wherein the molten metalremover is disposed opposite to the outer peripheral surface andincludes a heat dissipation surface to be in contact with the moltenmetal passing through the gap.
 10. The apparatus for producing a thinmetal strip according to claim 6, wherein the molten metal remover isdisposed opposite to the outer peripheral surface and includes a heatdissipation surface to be in contact with the molten metal passingthrough the gap.
 11. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 1, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 12. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 2, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 13. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 3, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 14. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 6, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 15. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 7, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 16. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 8, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 17. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 9, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 18. A method for producing a thin metal strip by asingle roll strip casting process using the apparatus for producing athin metal strip according to claim 10, the method comprising: a step ofsupplying the molten metal in the tundish onto the outer peripheralsurface of the cooling roll; a step of rapidly cooling the molten metalon the outer peripheral surface with the cooling roll to form the thinmetal strip; and a step of removing, with the molten metal remover, aportion of a thickness of the molten metal on the outer peripheralsurface that is larger than the width of the gap to cut down thethickness of the molten metal on the outer peripheral surface to thewidth of the gap.
 19. A method for producing a thin metal stripaccording to claim 18, wherein, the thin metal strip contains a chemicalcomposition, which contains Cu and Sn, and contains a phase which is D0₃in Strukturbericht notation.
 20. A method for producing a thin metalstrip according to claim 19, the chemical composition contains 10 to 20at % or 21 to 27 at % of Sn, with the balance being Cu and impurities.21. A method for producing a thin metal strip according to claim 20, thechemical composition contains, in place of a part of Cu, one or moreselected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Al,Si, B, and C.